If a node demand input wrong (e.g. 2400 gpm, insead of 24gpm), the adjacent nodes available fire flow will be very low, since that node absorb a lot available flow. So, please check the unusual water demands.

2. How to compare model result to the hydrant flow test result?

Hydrant flow test result will only consider a single point flow capacity at 20psi. A hydraulic model will consider a whole water distribution system (all the points within a pressure zone) to be above 20psi.

The field measured static pressure at a residual hydrant only indicates a normal operating pressure. If we calculate a huge demand of fire flow from a water source (e.g. tank, pumping station) to a job site, the operating pressures along the pipe route will drop, since the friction losses will increase dramatically. So, the field test static pressure is incomparable to a modeled operating pressure.

If you want to know the operating pressures along a pipe route, you may simulate the fire flow demand at one junction with a static flow analysis.

The City of Topeka periodically experiences red water in our water distribution
system. This red, or rust colored water occurs
in areas of the city with unlined cast iron water mains. Unlined cast iron mains
were used in Topeka until the mid 1950’s when the city began using
cement mortar-lined or plastic mains.

Unlined water mains rust over time
through a natural oxidation process. Contributing to the problem can be an
increase in salt levels in the Kansas River during low flow conditions.
Increased concentrations come from rivers and creeks in salt-rich western Kansas
that flow into the Kansas River. Salts such as sulfate and chloride are slightly
corrosive and cause older unlined iron water mains to dissolve more iron into
tap water.

Is Red Water Safe?All water produced by
the City of Topeka meets stringent guidelines set forth in the federal Safe
Drinking Water Act. Iron is an important mineral and the human body easily
discharges any excess. However, for individuals on a low iron diet, with
hypertension, or who are mixing infant formula, bottled water may be an
option.

Red Water SolutionsA short term low cost
solution to the red water problem is to flush water mains where red water is
occurring. Flushing water mains is not a long term solution. Once flushed, the
pipe will produce clear water for a time. However, red water will eventually
return.

The long term solution to red water comes at a higher financial
cost. That solution is replacement of the older unlined cast iron water mains
with cement mortar-lined or plastic pipe.

In order to understand it, you need to realize that theprovider almost
always bills more than is expected to be paid. So, even though $431.00
was billed, the provider is technically only able to bill $193.15. The
difference is written off and neither the insurance company nor the
patient is expected to be responsible for this amount. The provider
must adjust it off. The write off/adjustment process must take place
every time the provider sends a bill out. Patient responsibility such
as deductibles and co-insurance are calculated from the allowed amount,
not the original charge amount. Often, invoices are sent directly to
the patient before this process takes place. When the patient receives
the original bill before the write off process, the cost can seem
overwhelming. That is why it is important that the patient understands
the EOB and waits for the write-off process to occur before paying the
bill.

Wait for an EOB from your insurance company before paying for services
that appear on your physician’s invoice. If you have more than one
insurance company, wait for all EOB’s showing each determination.
Remember, the “billed amount” minus the “adjustment” or write-off equals
“allowed amount.” Patient responsibilities are based on this “allowed
amount” and subtracted from it before the physician gets a payment. The
physician will bill the amount marked “Patient Responsibility” on the
EOB. All this information should be conveyed in the patient bill.
Let’s look how this would appear based on the example EOB above.